.toTopButton {
    display: none;
    width: 50px;
    height: 50px;
    position: fixed;
    bottom: 16px;
    left: 50%;
    z-index: 999;
    border-radius: 25px;
    background: $White5 url("../img/toTopbtn_b.png") no-repeat 50% 50%;
    -webkit-transform: translateX(-50%);
    cursor: pointer;
    transition: background .5s;
    border: 1px solid $grey;
    &:hover {
        background-color: $White7 url("../img/toTopbtn.png") no-repeat 50% 50%;
    }
    &:active {
        background-color: $White9 url("../img/toTopbtn.png") no-repeat 50% 50%;
    }
}